1. Field of the Invention
This invention pertains to retorts for fluidized beds. More particularly, this invention pertains to a novel construction of a retort wall.
2. Description of the Prior Art
In the prior art, fluidized bed heat treatment is well known. Such heat treatment consists of fluidizing a bed of particulate material within a retort. The retort is commonly a vessel of stainless steel or the like.
One design of a retort is shown in commonly assigned and copending U.S. patent application Ser. No. 07/924,399. That patent application shows a stainless steel retort with infrared heating assemblies extending between the retort walls and submerged within a bed of fluidized particles. The infrared heating element assemblies of the prior art apparatus included a quartz tube which extends through opposing side walls of the retort. An infrared lamp is positioned concentrically within the tube.
Fluidized beds are also shown in U.S. Pat. Nos. 4,340,433 and 4,392,814 as reference items 10 in the drawings of those patents. As shown in U.S. Pat. No. 4,340,433, the retort 10 has an inner container which includes a corrugated side wall 12.
In practice, construction of a retort for a fluidized bed presents substantial fabrication problems. For example, during heat-up and operation of a fluidized bed, substantial temperatures are reached within the bed. This can result in significant thermal stresses and deformation in the retort wall. Further, in the aforementioned prior art apparatus quartz tubes are passed through the corrugated wall or other nonflat surfaces. The quartz tubes would pass through the corrugated wall. It is difficult to seal a quartz tube against such a nonflat surface.
It is an object of the present invention to provide a retort wall construction which overcomes the disadvantages of the prior art.